Practika (in the days when there was an East Germany to make copies of Western stuff) did a number of Pentax-style clones using a 42mm screw-in lens fitting (A bit like the Zenith, a similar, Soviet-made clone)
For insurance purposes, without wishing to be rude, you'd probably only get about thirty quid back for one that was nicked, because even when they were around they were very much at the entry level of SLR photography.
As for replacing it, you'll be lucky to find a Practika around these days - but you may find a Pentax Spotmatic or similar, which uses the same lens thread, and will be better made. If that's a bit steep, go for one of the Russian Zenith cameras; they have the same screw lens fitting as the Practika, a slightly less sophisticated but robust build and shouldn't cost you more than about £40 if you can find a second-hand example.
I used one for years with Pentax lenses - and as it's the glass on the front which gives you the image quality, it took some darned good pictures.